A user uses a mobile terminal such as a mobile phone (hereinafter, described as a PDA) at various places as in public transport such as a train or a bus, or at public facilities and so on. Accordingly, the PDA is used in an environment where other person is present. In such an environment, there is a case that other person peeks at a display screen of the FDA and this is undesirable from a view point of privacy protection. Accordingly, the PDA equipped with a peeking prevention function which can make a display screen difficult to see from a surrounding area by making a contrast difference in data for display displayed on a display unit of the PDA small is proposed.
For example, technology which, by setting an operation mode to a narrow view mode, makes a gradation difference of a display screen small and makes a display screen of the PDA difficult to peek at is disclosed by Japanese Patent Application Laid-Open No. 2008-20750. Also, technology which alters a display mode of a display screen of the PDA (such as character size or contrast) according to user's characteristics of mind and body (body-and-soul) or a usage environment is disclosed by Japanese Patent Application Laid-Open No. 2003-150291.